The invention relates to electronic interconnects, and more particularly to an adapter usable with interconnects for high speed signal transmission and control thereof.
Electronic test and measurement instrumentation is used to test electronic circuitry and devices. Typically, an instrument such as a digital analyzer or oscilloscope is used to test a device under test by contacting the device with an electronic or optical probe connected to the instrument via a cable. A connector on the end of the cable is plugged into a receptacle on the face of the instrument, so that high frequency signals are carried from circuitry on the probe to circuitry in the instrument.
In addition to the primary high frequency signal carried on the cable, other data signals may be carried between the probe and the instrument, such as to provide power and control signals to the probe, or to enable the instrument to actively monitor the high frequency signal only at selected times. Such systems use multiple contact connectors, with several data contacts adjacent a coaxial connector on the instrument/probe interconnect. Existing systems commonly use BNC connectors for the high frequency cable, with a connector housing on the cable supporting several pogo pins extending toward conductive lands on the instrument. To secure the cable, and to provide alignment, BNC connectors have proven effective. Some sampling oscilloscopes and other devices use SMA connectors with a separately connected bus for power and data control signals.
Backward compatibility is an issue for measurement instruments that have standard BNC or SMA type connectors without the power and data contacts. For example, Tektronix, Inc., Beaverton Oreg., manufactures active FET probes, such as the P6205 and P6217, that have multiple contact connectors adjacent to a BNC coaxial connector. To allow this type of probe to be used with a measurement instrument without such an interface, Tektronix manufactures and sells an 1103 TEKPROBE(copyright) Power Supply that allows those probes with power and data line contacts to be used with measurement instruments without such facilities. The 1103 TEKPROBE(copyright) Power Supply has a first interface connector mounted on the power supply that has a BNC type connector and adjacent contacts compatible with probes having the power and data contacts. A second standard BNC type connector is also mounted on the power supply that has its center conductor coupled to the center conductor of the first BNC type connector. The power supply further has voltage offset potentiometers and on/off switches. A power cable provides power to the power supply. The BNC/contact connector of the probe is connected to the first interface connector and a coaxial cable fitted with BNC type connectors is connected to the second BNC type connector and to the measurement instrument input BNC type connector. Voltage power to the probe is provided by the 1103 power supply as well as probe offset control voltage. The power supply, however, does not provide data stored in the probe to the measurement instrument nor does the instrument control the probe.
BNC interconnects employ rigid sleeves on each side that telescopically mate with each other to limit angular disposition of the cable connector from the chassis mounted connector. Robust mechanical support is important because probe cables may have heavy housings at the connector end to house electronic circuitry. In addition, BNC connectors have a bayonet connection system that provides rotational alignment of the connector housing, and which may be used to prevent unwanted extraction. While effective in some high frequency ranges, BNC connectors degrade signals for frequencies above about 1-3 GHz, depending on system demands and circuitry design.
Therefore, alternative high frequency tolerant connectors are used to insure signal integrity for frequencies above this range. Threaded connectors of some types such as the SMA standard can provide adequate high frequency performance (xcx9c12-20 GHz), but threaded connectors are not suited to uses with extra data connections, due to the connector housing and data contacts preventing access needed to rotate the threaded connector portion. A push-on or blind mate connector such as the BMA standard provides suitable high frequency performance, and avoids the incompatibility of threaded connectors with surrounding data connector housings.
However, BMA connectors are susceptible to damage when angularly disposed with more than a moderate force and do not provide any latching or retention mechanism. The shield or ground contact on a female portion of a BMA connector consists of a cylindrical chamber having an interior side wall lined by tiny leaf springs that conform to an inserted male shield contact. This conformity and flexibility provides the high frequency performance, even with slight angular misalignment. However, the delicate leaf spring contacts can be damaged by moderate angular forces on the connector, making a BMA connector unsuitable for labs where a protruding connector may be bumped or weighed down.
The embodiments disclosed herein overcome these limitations by providing an electronic interconnect assembly with a high speed coaxial interconnect for a coaxial transmission line having a central signal conductor and a surrounding shield conductor. The coaxial interconnect has a male side and a female side, with the female side including a shield sleeve having a chamber that receives a male shield contact on the male side. The shield sleeve has a contact with a compliant portion that flexibly grips the male shield contact. A mechanical alignment facility includes a closely mating pocket and body, each attached to a respective male or female side of the interconnect. Additional data and power connectors may be included with the pocket and body. To provide backward compatibility to measurement instruments not having such an interconnect assembly and to provide calibration facility for probes having such an interconnect assembly, a power and data interface adapter provides, at a minimum, power to the measurement probe and can also provide probe related data to and from the measurement instrument.